OBJECTIVE To derive new primate ES or EG cell lines; to expand neural precursor cells from primate ES cells; to generate primate ES cells MHC-matched to a specific individual. RESULTS We have demonstrated neural differentiation of rhesus ES cells in vitro in response to retinoic acid. FUTURE DIRECTIONS We will focus on genetic methods of purifying and expanding neural precursor cells more efficiently from primate ES cells, as a future source for transplantation. FUNDING Geron Corporation 133-BU-18 PUBLICATIONS Thomson, J.A., Marshall, V.S., and Trojanowski, J.Q. 1998. Neural differentiation of rhesus embryonic stem cells. AMPHIS 106 149-157.